Most aging Americans experience increased objective disturbances of initiating and maintaining sleep. Insomnia complaints are among the most important risk factors for institutionalization and early death among the elderly. likewise, depressive symptoms are colon and highly disabling, and the rate of suicide is increasing among elderly Americans. An ongoing survey shows that inadequate daylight exposures are associated with insomnia and depressive symptoms among adults 40-64 year of age. Preliminary studies and theoretical arguments indicate that insomnia and depression in aging Americans are partly caused by inadequate light exposure. This study will survey the prevalence of low illumination exposure in a representative sample of the San Diego population ages 60-79 years and will assess the epidemiologic associations of illumination with sleep and depressive symptoms. In a laboratory clinical trial, 135 volunteer subjects ages 60-79 will spend 5 nights and 4 days under controlled lighting conditions. With stratified randomization, 1/3 of subjects will be assigned to each of two experimental treatments using 3000 lux bright light for 4 hours each day. The final 1/3 of subjects will receive control 50 lux lighting and placebo dim red light treatment. Each subject will be monitored polysomnographically during the 8-hour sleep periods to determine the benefits of bright light treatment on objective sleep disturbances. Urine collections will be obtained to determine treatment effects on the circadian rhythm of melatonin excretion. Subjective sleep logs and mood self-ratings will assess subjective benefits of the treatments. By demonstrating casual benefits of bright light, this experiment will develop treatments with potentially high impact for millions of elderly Americans.